This invention relates generally to docking a tester to a probe station for testing integrated circuits in wafer form. More particularly, this invention relates to docking a Teradyne J750-type tester to a probe station using an A-type docking configuration.
Semiconductor testing of integrated circuits is required at various stages during the fabrication process. Each integrated circuit must be individually tested in wafer form and again in package form to ensure proper functionality. Whether in wafer form or package form, automated test equipment (ATE) transmits electrical signals to the integrated circuits and analyzes the responses to determine whether the circuits are properly operating.
In wafer form, the integrated circuits are tested using a probing system. The probing system includes a probing station (often called a prober) that moves the wafer to properly align each integrated circuit to be tested by the ATE (often called a tester). A probe card is mounted in a stationary position on the probe station and contains several hundred needles used to establish electrical contact with pads on the integrated circuit under test. A pogo tower is used to mechanically connect the tester with the probe station. More specifically, the pogo tower is brought into electrical contact with a test board or motherboard on the tester and with the probe card on the probe station. The tester then transmits electrical signals to the integrated circuit and analyzes the responses.
FIG. 1 shows a generic example of a tester, including a test head 10, mounted on a probe station 12. A test-head positioning system 14 is used to lift and lower the test head 10, which can weigh between 500 and 1000 lbs. The positioning system must be manipulated to properly align the tester with the probe card (not shown).
The testers can also be used during a separate stage of the fabrication process. More particularly, after the integrated circuits have been tested in wafer form using the probe station, the wafer is cut up and the individual integrated circuits are packaged. These individual chips are tested in a unit called a handler. When using the handler, instead of having a tester vertically lowered onto a probe station, the tester is mounted to the side of the handler. FIG. 2 shows a generic example of a tester 20 being mounted to a handler 22.
To align the tester with the probe station or handler, docking hardware is used that secures the tester in proper mechanical and electrical contact with the probe station or handler. In the case of mounting a tester to a probe station, the docking hardware is kinematic docking using a male portion on the tester and a female portion on the probe station. Once docked, the tester is properly aligned in relation to the probe station and the compression between the motherboard, pogo tower, and probe card are such that good contact is ensured.
Currently, all probe stations use a docking configuration called a B-type docking configuration. FIGS. 3 and 4 show examples of a B-type docking configuration used on many probe stations including probe stations manufactured by companies such as TSK(copyright), EG(copyright), and Tel(copyright). The B-type docking configuration has kinematic docking units 26 at three corners of the mechanical interface. Although the fourth corner remains unattached, the mechanical interface is sufficient because the weight of the tester helps hold the tester in proper position above the probe station.
On the other hand, handlers use an A-type docking configuration shown in FIG. 5. The A-type docking configuration has kinematic docking units 30 on two corners and a third docking unit 32 centrally positioned on the opposite side from units 30. With the side mounting of the tester to the handler, the A-type configuration is preferable because it can better support the weight of the tester than the B-type docking configuration, which has an unattached corner.
Testers, such as the Teradyne J750, are several million dollars to purchase. The Teradyne J750 has an A-type configuration and, consequently, cannot be mounted to any existing probe station. Thus, a tester with an A-type configuration (e.g., the J750) that is mountable to a handler cannot then be used for testing on a probe station that has a B-type configuration. Thus, currently manufacturers must purchase two separate testersxe2x80x94one with an A-type configuration and one with a B-type configuration.
It is desirable to provide a system that allows the tester, such as the Teradyne J750, to be efficiently used with both a handler and a probe station.
The present invention allows a Teradyne J750-type tester to be mounted to both a probe station and a handler using uniform docking hardware. Handlers already have an A-type configuration for mounting to the J750. The present invention converts any desired probe station into an A-type configuration so that the J750 may be used on both probe stations and handlers. Thus, using the present invention, manufacturers of integrated circuits will need to buy fewer testers resulting in a large savings in capital expenditure.
In one aspect, a variety of headstages are designed so that the headstages fit to different types of probe stations. The head stages are designed to mount uniform docking hardware that converts the probe stations to an A-type configuration. As a result, the J750-type tester can be mounted to both handlers and a wide variety of probe stations.
In another aspect, two separate mounting assemblies are used. One of the mounting assemblies has two kinematic docking units placed thereon. The other of the mounting assemblies has a single kinematic docking unit. The separate mounting assemblies allows ease of assembly to the probe station and allows the mounting assemblies to be manufactured for low cost.
In yet another aspect, locator pins are situated on the headstage to ensure proper placement of the mounting assemblies.
These and other aspects of the invention will become apparent from the following detailed description, which makes references to the accompanying drawings.